Electronic devices, such as semiconductor devices, memory chips, microprocessor chips, and imager chips, can include a charge pump (e.g., a DC to DC converter that functions as a power source) to create a voltage different (e.g., higher or lower) than the available source voltage (e.g., Vdd). Charge pumps can include components (e.g., diodes, switches, comparators, capacitors, resistors, or a combination thereof) that are organized to provide an output voltage that is boosted or reduced from an incoming source voltage.
Some charge pumps (e.g., reconfigurable charge pumps) can include the components arranged in units or stages, such that the connections between or relative arrangements of the units can be reconfigured in real-time to adjust one or more capabilities of the charge pump. FIG. 1A, illustrates a single stage of a charge pump in an electronic device 101. In a pre-charge phase, an energy storage structure (e.g., one or more capacitors) in the single stage can be charged using a voltage supply (e.g., providing a voltage level of ‘Vin’). As illustrated in FIG. 1B, the charged storage structure can be reconfigured (e.g., using one or more relays or switches) from a parallel connection with the voltage supply for the pre-charge phase to a series connection with the voltage supply for a boost phase. Accordingly, a resulting output (e.g., ‘Vout’) can be higher (e.g., ‘2Vin’) than the voltage level of the supply (e.g. ‘Vin’).
The output voltage can be used to drive a load as illustrated in FIG. 1C. The boosted output can be connected to the electrical load. The load can have a current (e.g., as represented ‘Iload’) and/or a capacitance level (e.g., as represented by a capacitance ‘Cload’). As such, when the load is connected to the charge pump, the output voltage (e.g., ‘Vout’) can drop according to the pump capability. Accordingly, multiple units or stages can be connected in series or in parallel to provide and/or maintain a targeted level of voltage, current, power, etc. to the connected load.
As illustrated in FIG. 1D, the electronic device 101 can include a reconfigurable charge pump 102, a pump regulator 104 (e.g., a mechanism, such as a software or firmware module, circuitry, or a combination thereof), firmware 130, or a combination thereof. The reconfigurable charge pump 102 can include pump units 106 (e.g., groupings or stages of components or circuits configured to produce or contribute to a level of output voltage (“Vout”)) that can be configured in series (e.g., in stages) or parallel (e.g., array configuration) connections relative to each other. For example, the pump units 106 can be configured or connected (e.g., using switches or relays) to form a series set 108 (e.g., a set of stages of the pump units 106 that are connected electrically in series), or a parallel set 110 (e.g., a set of arrays of the pump units 106 or the series sets that are connected electrically in parallel). A stage count 112, shown as ‘N’ in FIG. 1D, can represent a quantity of the pump units 106 within each of the series set 108. An array count 114, shown as ‘M’ in FIG. 1D, can represent a quantity of the pump units 106 or the series sets connected in parallel within the parallel set 110.
The pump regulator 104, the firmware 130, or a combination thereof can control the reconfigurable charge pump 102, such as by commanding the reconfigurable charge pump 102 to turn on or off. Further, the firmware 130 can be configured to control the reconfigurable charge pump 102, such as by configuring the pump units 106 in the reconfigurable charge pump 102. The firmware 130 can adjust the stage count 112 and the array count 114 (e.g., where the stage count 112 and the array count 114 are inversely proportionate) to adjust the output voltage. For example, the firmware 130 can configure the reconfigurable charge pump 102 to have the pump units 106 connected individually and with a number of arrays equal to a product between ‘N’ and ‘M’ (e.g., 1 stage by N·M arrays). Also for example, the firmware 130 can configure the reconfigurable charge pump 102 as the series set 108 including 2 stages and further connected with the number of arrays reduced by a factor of 2 (e.g., 2 stages by (N/2)·M arrays). Also for example, the firmware 130 can configure the reconfigurable charge pump 102 as the series set 108 including 4 stages and further connected with the number of arrays further reduced by a factor of 2 (e.g., for a 4 stage by (N/4)·M arrays). The firmware 130 can increase the stage count 112 (e.g., also decreasing the parallel set 110) to increase a maximum possible the output voltage (“Vmax”), where the maximum would be increased in proportion to the stage count 112 (e.g., Vmax=Vin(1+N)).
As illustrated in FIG. 2, output current (e.g., as illustrated by linear solid lines) and power efficiency (e.g., as illustrated by dotted curves) can be affected by controlling connections or configurations of the reconfigurable charge pump 102 (e.g., corresponding to increasing the output voltage). For example, the output current (e.g., Ieff, approximated by 1/[N+1]) can decrease in a linear pattern as the output voltage increases, and the slope of the linear pattern can decrease as the number of series connections increase (e.g., thereby increasing the maximum for the voltage output). The output current can be a function of effective output resistance of the pump (“Rout”), which is a function of the stage count 112, clock frequency, and capacitance level (e.g., such as for Rout=N/[fclk·Cp]). Also for example, the power efficiency (e.g., Peff=(Ieff·Vout)/Vin) can behave as a convex curve, where the power efficiency decreases after a certain level of the output voltage. Further, the maximum level of the power efficiency reduces as the number of series connections increase. As such, for low levels of the output voltage, decreasing the stage count 112 improves the output current and the power efficiency.